This disclosure relates to internal combustion engines and, more particularly, to operating internal combustion engines having exhaust gas recirculation.
Exhaust gas recirculation (“EGR”) involves introduction of a portion of exhaust gases from an internal combustion engine back into a combustion chamber of the internal combustion engine, such as one or more cylinders of the internal combustion engine. EGR can be used to reduce formation of nitrogen oxides, such as, for example, nitrogen oxide (NO) and nitrogen dioxide (NO2) (referred to collectively hereinafter as “NOx”). The exhaust gas is substantially inert. Thus, introducing a portion of the exhaust gas into the combustion chamber of an internal combustion engine dilutes the mixture of fuel and air to be combusted, and resultantly lowers the peak combustion temperature and excess oxygen. As a result, the engine produces reduced amounts of NOx because NOx forms much more quickly at higher temperatures. Thus, EGR reduces or limits the amount of NOx generated during combustion of the engine.